Clarke received early encouragement in his writing in high school, and in college won prizes for several of his poems. Clarke went on to write as a journalist before settling on fiction as his preferred genre.

Clarke is known for his novels and short stories which focus on the struggles of black people attempting to succeed in white society. Anthony Boxill notes that Clarke "became the foremost recounter of the black West Indian immigrants' experience in Canada." Boxill describes the overriding tone of Clarke's fiction in regard to race relations: "Of his generation of West Indian novelists he is perhaps the most outspoken and bitter in depicting the experience of the poor black when confronted with the establishment, whether it is that of the white majority in Canada, the colonial expatriate, or the postcolonial ruling black middle class in Barbados."